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arxiv: 2606.11788 · v1 · pith:WPSAJ7H2new · submitted 2026-06-10 · 🌌 astro-ph.HE

Centrifugal instability of compressible flows and the hydrodynamic stability of accretion disks

Pith reviewed 2026-06-27 09:01 UTC · model grok-4.3

classification 🌌 astro-ph.HE
keywords centrifugal instabilitycompressible flowsRayleigh criterionSolberg-Høiland criterionaccretion diskshydrodynamic stabilityMach number
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The pith

The centrifugal instability of compressible rotating flows depends on Mach number even in the Newtonian limit.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper establishes a generalization of the Rayleigh criterion for centrifugal instability in pressure-supported compressible rotation. This generalization shows that instability is strongly affected by the flow Mach number, applying in both relativistic and Newtonian limits. Axisymmetric numerical simulations of non-relativistic transonic rotating flows confirm the criterion by matching predicted stability outcomes. For flows rotating about a central compact object, the derived instability criterion proves equivalent to the standard Solberg-Høiland criterion.

Core claim

A generalization of the Rayleigh criterion for compressible relativistic rotation shows the centrifugal instability depends on the flow Mach number. This holds in the Newtonian limit as well. Simulations of transonic rotating flows stable under the original Rayleigh criterion but potentially unstable under the new one agree perfectly with the theory. The criterion for accretion disks is equivalent to the Solberg-Høiland criterion, which lacks explicit Mach number dependence.

What carries the argument

The Mach-number-dependent generalization of the Rayleigh criterion for pressure-supported compressible rotation.

If this is right

  • Simulations of non-relativistic transonic flows agree perfectly with the Mach-dependent criterion.
  • The criterion applies to both relativistic and Newtonian compressible flows.
  • The derived criterion for pressure-supported rotation about a central object is equivalent to the Solberg-Høiland criterion.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Stability analyses of highly supersonic accretion disks that rely solely on the classical Rayleigh criterion may overlook Mach-number effects that the equivalent Solberg-Høiland form already incorporates.
  • The analogy between centrifugal force and gravity in the stability criteria suggests similar Mach-dependent generalizations could apply to other rotating astrophysical flows.

Load-bearing premise

The generalization of the Rayleigh criterion to compressible pressure-supported rotation is taken as given from prior analysis.

What would settle it

An axisymmetric simulation of a transonic Newtonian rotating flow that is stable according to the classical Rayleigh criterion but shows instability (or vice versa) according to the Mach-dependent criterion.

Figures

Figures reproduced from arXiv: 2606.11788 by Konstantinos N. Gourgouliatos, Serguei S. Komissarov.

Figure 1
Figure 1. Figure 1: Stable and unstable domains in the models with p0 = 0.1 (top panel) and in the models with p0 = 1.0 (bottom panel). In the unstable domains, d ln Ψ/d ln R − M2 < 0. These structures are reminiscent of numerical fluid jets stud￾ied in connection to the jets of active galactic nuclei. The jets may extend well beyond the instability domain and cre￾ate an extended zone of turbulent flow. For example, the insta… view at source ↗
Figure 2
Figure 2. Figure 2: The density distribution at t = 10, 15, 50 for the model CYL-C (top panels), CYL-D (middle panels) and CYL-F (bottom panels). For instability, the force derivative has to be positive, and hence the instability criterion reads ρv2 ϕ R2 d ln Ψ d ln R − M2 R dp dR + GM R2 ρ γ dS dR < 0 . (23) To understand the physical nature of the instability, it is instructive to consider the limits of vanishing gravity an… view at source ↗
read the original abstract

A recent analysis of the centrifugal instability in the case of pressure-supported compressible relativistic rotation, with application to astrophysical jets, yielded a generalisation of the famous Rayleigh criterion for Newtonian flows. According to this criterion, the centrifugal instability is strongly affected by the flow Mach number, and not only in the relativistic fluid dynamics but also in its Newtonian limit. To validate the Newtonian version of this criterion, we performed axisymmetric numerical simulations of non-relativistic transonic rotating flows which are stable according to the original Rayleigh criterion but can be either stable or unstable according to the new one. The results of computer simulations are found to be in perfect agreement with the theory. The hydrodynamic stability of accretion disks is often explained by referring to the original Rayleigh criterion, even if their rotation is highly supersonic. To clarify the matter, we analysed the hydrodynamic stability of flows rotating about central compact object and derived an instability criterion that retains the explicit dependence on the flow Mach number. This criterion turns out to be equivalent to the standard Solberg-H{\o}iland criterion, which does not involve the Mach number. The same applies to the case of pressure-supported rotation, where the role of gravity is played by the centrifugal force.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 2 minor

Summary. The paper generalizes the Rayleigh criterion for centrifugal instability to compressible pressure-supported rotation, showing Mach number dependence even in the Newtonian limit. It validates the Newtonian transonic case via axisymmetric simulations of flows stable by the original Rayleigh criterion but potentially unstable by the new criterion, reporting perfect agreement with theory. For accretion disks, it derives a Mach-dependent instability criterion shown to be equivalent to the standard Solberg-Høiland criterion.

Significance. If the results hold, the work supplies targeted numerical validation for the compressible generalization in the Newtonian regime and resolves applicability questions for supersonic accretion disks by establishing mathematical equivalence to the Solberg-Høiland criterion. The simulation agreement and the equivalence demonstration are explicit strengths that support the central claims without introducing free parameters.

major comments (1)
  1. The validation of the Newtonian transonic case rests on the claim that simulation results are in 'perfect agreement' with the generalized criterion. The manuscript should report quantitative measures of this agreement (e.g., comparison of measured growth rates to theoretical predictions) and details on simulation parameters such as resolution, initial perturbation amplitudes, and case selection criteria to substantiate the load-bearing validation result.
minor comments (2)
  1. The abstract states that the disk criterion 'turns out to be equivalent' to Solberg-Høiland; the main text should include an explicit cross-reference to the equations or subsection where the algebraic equivalence is demonstrated.
  2. Clarify in the introduction or methods the precise scope of the new contribution versus the referenced prior compressible generalization to avoid any ambiguity about what is being validated here.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for the careful review and the recommendation of minor revision. The single major comment concerns the presentation of the numerical validation, which we address below.

read point-by-point responses
  1. Referee: The validation of the Newtonian transonic case rests on the claim that simulation results are in 'perfect agreement' with the generalized criterion. The manuscript should report quantitative measures of this agreement (e.g., comparison of measured growth rates to theoretical predictions) and details on simulation parameters such as resolution, initial perturbation amplitudes, and case selection criteria to substantiate the load-bearing validation result.

    Authors: We agree that the current description of the simulation results would benefit from quantitative support. In the revised manuscript we will add a direct comparison of the growth rates extracted from the simulations against the analytic predictions of the generalized criterion, together with the requested technical details on resolution, initial perturbation amplitudes, and case selection. These additions will be placed in the section describing the Newtonian validation runs. revision: yes

Circularity Check

0 steps flagged

No significant circularity; derivation chain is self-contained

full rationale

The paper imports the compressible generalization of the Rayleigh criterion from a cited prior analysis but does not claim to re-derive it here; instead it validates the Newtonian transonic case via independent axisymmetric simulations of flows stable under the original Rayleigh criterion. The accretion-disk criterion is derived directly in the present work and shown mathematically equivalent to the Solberg-Høiland criterion through the paper's own analysis, without any reduction of predictions to fitted parameters, self-definitional loops, or load-bearing self-citations that lack external verification. No step equates an output to its input by construction.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Based on abstract only; no explicit free parameters, axioms, or invented entities are stated. The work relies on standard assumptions of ideal fluid dynamics and axisymmetric perturbations.

pith-pipeline@v0.9.1-grok · 5749 in / 1144 out tokens · 16945 ms · 2026-06-27T09:01:14.127753+00:00 · methodology

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Reference graph

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